That is to say, Marc Dionne's lab, at King's College London; not to be confused with any other Dionne lab.

That is to say, Marc Dionne's lab, at King's College London; not to be confused with any other Dionne lab.

-

We are interested in (1) the effects of host genetics on the biology of infection; and (2) cytokine signalling and its effects on immune and non-immune tissues. ''Drosophila melanogaster'' is our animal model of choice.

+

We are interested in (1) metabolic-immune interaction and its effects on the biology of infection; and (2) cytokine signalling and its effects on immune and non-immune tissues. ''Drosophila melanogaster'' is our animal model of choice.

Work in the lab has been funded by [http://www.bbsrc.ac.uk the Biotechnology and Biological Sciences Research Council] and [http://www.wellcome.ac.uk the Wellcome Trust].

Work in the lab has been funded by [http://www.bbsrc.ac.uk the Biotechnology and Biological Sciences Research Council] and [http://www.wellcome.ac.uk the Wellcome Trust].

-

==Host genetics and the biology of infection==

+

==Metabolic-immune interaction and host genetics in infection==

-

Different individuals show different levels of resistance to infections and develop different pathologies in response to infections. We are interested in why this is the case. We use the fruitfly ''Drosophila melanogaster'' as a model host to study these questions; this allows us to screen for genes that affect the progress of infection in a rapid and unbiased fashion.

+

It has been known for centuries that chronic infections cause systemic metabolic disruption, but it is fundamentally unclear why and how these events are linked. Does metabolic disruption somehow favor the host response to infection? If so, how? We address these fundamental biological questions by analyzing pathogenic infections and their consequences in the fruit-fly ''Drosophila melanogaster''. We use classical ''Drosophila'' genetics, computational analysis and modeling of gene expression, biochemistry, and intravital microscopy to probe the metabolic-immune interface.

-

All of our experiments originate from a simple genetic screen. Mutant flies are infected with ''Mycobacterium marinum'', a bacterium closely-related to the causative agent of tuberculosis, or with ''Mycobacterium smegmatis'', a related non-pathogen. We select lines of flies that die more quickly or more slowly than wild-type controls and identify the mutation that gives rise to this phenotype. We then try to understand what this phenotype tells us about the function of the mutated gene.

+

One pathogen of particular interest to us is ''Mycobacterium marinum''. We have previously shown that flies infected with ''M. marinum'' exhibit progressive loss of metabolic stores accompanied by mild hyperglycemia. We have shown that these effects are caused, in part, by systemic disruption of signaling via the anabolic effector kinases Akt and p70 S6 kinase. The transcription factor MEF2 responds to nutrient signals to regulate expression of both immune effectors and anabolic enzymes. Remarkably, though MEF2 promotes the expression of both groups of genes, its choice of targets is regulated by a conserved phosphorylation that alters its affinity for the TATA binding protein. It appears that the disruption of anabolic kinase activity may be required to permit MEF2 to drive the antibacterial response. [http://www.cell.com/abstract/S0092-8674(13)01144-6 This work has recently been published in ''Cell''.]

-

So far, our work on this system has focused on the mechanisms of pathogenesis. We have found that this infection causes progressive loss of metabolic stores, broadly similar to the wasting seen in people with tuberculosis. We have shown that, in the fly, this wasting effect is caused partly by systemic failures in anabolic signals via the insulin effector Akt and the TOR effector p70 S6 kinase.

+

Ongoing work continues to explore other metabolic inputs into MEF2, other targets of MEF2 in its two discrete physiological states, and the pathways by which infection disrupts anabolic kinase activity.

-

+

-

Most recently, we have shown that the transcription factor MEF2 responds to nutrient signals to regulate expression of both immune effectors and anabolic enzymes. Remarkably, though MEF2 promotes the expression of both groups of genes, its choice of targets is regulated by a conserved phosphorylation that alters its affinity for the TATA binding protein. [http://www.cell.com/abstract/S0092-8674(13)01144-6 This work has recently been published in ''Cell''.]

+

==Cytokines and cytokine signalling==

==Cytokines and cytokine signalling==

-

In the course of screening, we find a lot of molecules and pathways that end up being involved in cytokine signalling and its consequences. One aspect of this is the metabolic effects of infection, which appear to result from high levels of cytokine expression over several days. Cytokines also regulate the realized immune response of the fly, much as they do in mammals.

+

In the course of screening for mutants with defective responses to ''M. marinum'', we find a lot of molecules and pathways that end up being involved in cytokine signalling and its consequences. Cytokines regulate the realized immune response of the fly, much as they do in mammals; they also can be significant direct drivers of pathology due to effects on immune and nonimmune target tissues. However, very little is known about the biology of cytokines in ''Drosophila melanogaster'', especially in the context of bacterial infections.

+

+

Some time back, we showed that two different TGF-betas regulate fly immunity, each inhibiting a specific arm of the immune response, and each being produced by only a subset of phagocytes. [http://www.cell.com/current-biology/abstract/S0960-9822(11)00954-7 Check it out!] More recently, we have been analyzing the role of an interleukin-like signal in ''Mycobacterium marinum'' infection - we hope to be able to say more about this soon.

+

+

==Positions available==

-

Some time back, we published some of this work in ''Current Biology'', showing that two different TGF-betas regulate fly immunity, each inhibiting a specific arm of the immune response, and each being produced by only a subset of phagocytes. [http://www.cell.com/current-biology/abstract/S0960-9822(11)00954-7 Check it out!]

+

A funded postdoctoral position is currently available. More generally, we are always interested in hearing from potential graduate students and post-docs. If you are interested in our work, get in touch!

Contents

Welcome to the Dionne lab!

That is to say, Marc Dionne's lab, at King's College London; not to be confused with any other Dionne lab.

We are interested in (1) metabolic-immune interaction and its effects on the biology of infection; and (2) cytokine signalling and its effects on immune and non-immune tissues. Drosophila melanogaster is our animal model of choice.

Metabolic-immune interaction and host genetics in infection

It has been known for centuries that chronic infections cause systemic metabolic disruption, but it is fundamentally unclear why and how these events are linked. Does metabolic disruption somehow favor the host response to infection? If so, how? We address these fundamental biological questions by analyzing pathogenic infections and their consequences in the fruit-fly Drosophila melanogaster. We use classical Drosophila genetics, computational analysis and modeling of gene expression, biochemistry, and intravital microscopy to probe the metabolic-immune interface.

One pathogen of particular interest to us is Mycobacterium marinum. We have previously shown that flies infected with M. marinum exhibit progressive loss of metabolic stores accompanied by mild hyperglycemia. We have shown that these effects are caused, in part, by systemic disruption of signaling via the anabolic effector kinases Akt and p70 S6 kinase. The transcription factor MEF2 responds to nutrient signals to regulate expression of both immune effectors and anabolic enzymes. Remarkably, though MEF2 promotes the expression of both groups of genes, its choice of targets is regulated by a conserved phosphorylation that alters its affinity for the TATA binding protein. It appears that the disruption of anabolic kinase activity may be required to permit MEF2 to drive the antibacterial response. This work has recently been published in Cell.

Ongoing work continues to explore other metabolic inputs into MEF2, other targets of MEF2 in its two discrete physiological states, and the pathways by which infection disrupts anabolic kinase activity.

Cytokines and cytokine signalling

In the course of screening for mutants with defective responses to M. marinum, we find a lot of molecules and pathways that end up being involved in cytokine signalling and its consequences. Cytokines regulate the realized immune response of the fly, much as they do in mammals; they also can be significant direct drivers of pathology due to effects on immune and nonimmune target tissues. However, very little is known about the biology of cytokines in Drosophila melanogaster, especially in the context of bacterial infections.

Some time back, we showed that two different TGF-betas regulate fly immunity, each inhibiting a specific arm of the immune response, and each being produced by only a subset of phagocytes. Check it out! More recently, we have been analyzing the role of an interleukin-like signal in Mycobacterium marinum infection - we hope to be able to say more about this soon.

Positions available

A funded postdoctoral position is currently available. More generally, we are always interested in hearing from potential graduate students and post-docs. If you are interested in our work, get in touch!